1. Field of the Invention
The present invention relates generally to a magnetic recording and reproducing apparatus for recording information in a magnetic recording medium and for reproducing the recorded information from the magnetic recording medium.
2. Description of the Prior Art
In a floppy disk device (referred to as FDD hereinafter) used s an external storage device for an electronic computer, information is recorded in a flexible magnetic disc (referred to as a disk hereinafter) or reproduced therefrom through a magnetic recording and reproducing head (referred to as a R/W head) on the basis of electric-to-magnetic transduction (referred to as electromagnetic transduction hereinafter). In this FDD field, conventionally, a horizontal (in-plane) magnetic recording technique has been adopted such that information is recorded when the magnetic material is magnetized in the horizontal direction or along the surface of the disk. Recently, however, a perpendicular magnetic recording technique in which information is recorded when the magnetic material is magnetized in the vertical direction of the surface of the has been developed. In this perpendicular magnetic recording method, since two adjacent magnetization directions are opposite to each other and therefore strong residual magnetization can be maintained, it is possible to improve the recording density (referred to as BPI (bit per inch) hereinafter) up to about several times that of the horizontal recording medium. For example, the recording density is about 9K BPI in the horizontal recording medium, and about 40 K BPI in the perpendicular recording medium.
Since apparatuses of the perpendicular magnetic recording type have been developed, the storage capacity of the disk has been increased markedly. However, it is desirable that a disk in which information is recorded in accordance with the horizontal magnetic recording method also be usable in common, for the magnetic recording and reproducing apparatus of the perpendicular magnetic recording type, from the standpoint of availability of recorded information. However, since the BPI greatly differs between the horizontal and perpendicular recording mediums that is, since there exists a big difference in electromagnetic transduction performance or characteristics between the two, it is impossible to stably record information in the two disks or to reproduce the recorded information therefrom. Therefore, these exists a problem in that it is impossible to use in common a floppy disk in which information is recorded so as to correspond to an apparatus of the horizontal magnetic recording of the perpendicular magnetic recording type